Multi-focal intraocular lens system and methods

ABSTRACT

The invention pertains to methods, components, and operations of multi-focal intraocular lens systems, including range finding for driving same and for discriminating between multiple objects and varying brightness conditions. The invention also pertains to intraocular photosensors and range-finding methods to be used with intra-ocular lens systems, and components, that provide multi-focal IOL capabilities in dynamic visual environments.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to and benefit of, U.S. ProvisionalPatent Application Ser. No. 60/953,640, filed Aug. 2, 2007, the contentsof which are incorporated herein by reference.

FIELD OF INVENTION

Example aspects of the present invention generally relate to multi-focalintraocular lens (“IOL”) systems, and more particularly to intraocularphotosensors and range-finding methods to be used with IOL systems andcomponents that provide multi-focal IOL capabilities in dynamic visualenvironments.

DESCRIPTION OF THE RELATED ART

In the human visual system, in order to selectively focus on nearbyobjects such as those less than 20 feet away, the focal length of aneye's lens must change. In a normal eye, this is achieved through thecontraction of a ciliary muscle that is mechanically coupled to thelens. The extent of contraction of the ciliary muscle deforms the lensthereby changing the focal length, or power, of the lens. By selectivelydeforming the lens in this manner it becomes possible to focus onobjects that are at different distances from the eye. This process ofselectively focusing on objects at different distances is referred to asaccommodation.

A diopter (“D”) is a unit of measurement of the refractive power oflenses equal to the reciprocal of the focal length measured in meters.In humans, the total power a relaxed eye is approximately 60 diopters.The cornea accounts for approximately two-thirds of this power and thecrystalline lens contributes the remaining third. As humans age, theamplitude of accommodation reduces from approximately 15 to 20 dioptersin the very young, to about 10 diopters at age 25, to around 1 diopterat 50 and over. In the case of a 50 year old and whose lens system canonly provide 1 D of accommodative power, this means that the closestobject on which the individual can clearly focus is at a distance of 1meter (1 meter= 1/1 diopter). Similarly, 2 D will allow accommodativefocus on an object which is ½ meter distant, 3 D will allow focus on anobject ⅓ meter distant, and so on.

The ability to accommodate or see clearly at near distances can bereduced or eliminated for a variety of reasons, including: injury,disease, or the natural aging process. For example, as a person ages,the natural crystalline lens of the eye loses plasticity and it becomesincreasingly difficult to deform the stiffening lens to achieveaccommodation sufficient to focus on objects at different nearbydistances.

Cataract is a disease associated with aging in which the naturalcrystalline lens becomes cloudy and more opaque, reducing visionsignificantly. Cataracts typically occur after the loss ofaccommodation. Intraocular lenses (“IOLs”) have been used in the UnitedStates since the late 1960s to restore vision to patients suffering thisdisease, and more recently are being used in several types of refractiveeye surgeries. IOLs are typically permanent, plastic lenses that aresurgically implanted inside of the eyeball to replace or supplement theeye's natural crystalline lens.

IOLs can also serve to compensate for loss of refractive function of thehuman eye. Accommodative IOLs have been introduced, for example, whichchange focus by movement (e.g., physically deforming and/or translatingwithin the orbit of the eye) as the muscular ciliary body reacts to anaccommodative stimulus from the brain, similar to the way the body'snatural crystalline lens focuses. Unfortunately, these types ofaccommodative IOLs are substantially inferior in performance whencompared to a healthy natural crystalline lens, and fail to have thecapability to accurately and reliably focus on demand.

An IOL system that will be capable of accommodation and that candynamically adjust its focal length on objects of varying distancesshould be able to accurately determine the distance to the object offocus, also commonly referred to as the object of regard. That is, to beable to adjust the focus of the visual system in order to bring nearobjects of regard in optimum focus, the distance to the object of regardshould be known.

In order to achieve accurate multi-focal capabilities, e.g.,accommodation, an IOL system should also be able to rapidly andaccurately determine the distance to the object of regard on anintermittent and preferably continuous basis so that the dynamicallyfocusing lens system can adjust to the proper focus based on thedistance to the object of regard.

There have been several methods proposed for determining the distance tothe object of regard, or range-finding. Examples include using aradar-like approach, where an infrared beam and sensor are incorporatedinto a lens system and used to detect or target distance throughtransmission, reflection, sensing, and signal processing. Anotherproposed range-finding technique uses a piezoelectric crystal attachedto the ciliary muscle and infers the distance to the object of regard bythe voltage generated by the crystal in response to degree of theciliary muscle contraction that accompanies and purportedly indicatesthe degree of accommodation sought by the visual system. The ciliarybody is known to be very fragile and difficult to work with, however,making these solutions relatively complex and unappealing.

Other proposed range-finding methods involve repeatedly measuring thecontrast of an image while the focus of the optical system iscontinuously adjusted until a contrast maximum is detected at whichpoint the object is considered in focus. A significant problem with thisapproach, however, is that often there are multiple objects in the lineof vision, making it difficult or unable to distinguish between thedesired object of regard and an intervening object (e.g., raindrops).

A need exists for an accurate and reliable way to determine the distanceto an object of regard in an accommodative IOL system and todiscriminate between various visual ambient conditions such as lightingvariations and multiple objects. A further need exists for arange-finder that can be simply integrated into an IOL system and whichdoes not negatively impact the visual system either anatomically,physiologically, or with respect to acuity. Yet another need exists fora dynamic multi-focal IOL system including a range-finding componentcapable of discriminating between distances to objects of regard invarious ambient lighting conditions and for distinguishing changes inambient lighting conditions.

SUMMARY OF THE INVENTION

In one embodiment, an intraocular photosensor design is used to measurepupil diameter, and changes thereto, by detecting changes of incidentlight intensity and distribution through the pupil to determine thepupil size. In this embodiment a photosensor is placed posterior anddirectly in line with the pupil, in a relatively coplanar relationship.One or more linear arrays of photosensitive elements are included, thenumber of elements being sufficient to discriminate between pupil sizechanges, while the photosensor remains sufficiently transparent.

In one embodiment, the pupil size determination is used to estimate adistance to an object of regard based on a relationship between thepupil size and ocular convergence, or near-synkinesis. In anotherembodiment, the determined distance to the object of regard is used asinput to drive a dynamically focusable intraocular lens system in orderto bring the object of regard in or near focus. In a further embodimentthe programmable photosensor is utilized as the primary range-finder inan IOL system. In yet another embodiment, the determination of the pupilsize is used as a supplemental or complementary method of range finding,or for determining the distance to objects of regard.

In another embodiment the sensor is integrated with an intraocular lenssystem. The intraocular lens system is a multi-focal lens system in oneembodiment, and may comprise electroactive lens elements, or othermulti-focal lens configurations, and further comprises amicrocontroller, actuator, and power supply means for controlling,actuating, and powering the lens system. In an embodiment, thephotosensor is integrated with an electroactive pixelated array lenssystem capable of sensing incident light in order to determine pupilsize, determine object distance, and adjust the focal power of the lenssystem to focus on the object. In another embodiment, the photosensor isintegrated with a non-pixelated electroactive lens system. In stillanother embodiment, the photosensor is integrated with or a component ofa non-electroactive focusing system.

One embodiment of the invention comprises an intraocular lens systemcomprising, a multi-focal lens system for adjusting the power of thefocal system, a range-finder for determining the distance to the objectof regard, a controller and actuator for controlling and driving themulti-focal lens system, and a power source for powering the componentsof the system. In one embodiment, the range-finder comprises anintraocular photosensor and associated processing means for determiningthe distance to an object of regard based on pupil diameter. In anotherembodiment, the range finder comprises a photosensor which utilizesrange-finding technologies such as contrast measurements techniques, inaddition to pupil size measurement to more accurately and reliablydetermine the distance to the object of regard. In another embodiment,the photosensor is integral with the lens system. In still anotherembodiment, the photosensor is a physically separate and modularcomponent of the overall system. In one embodiment, the photosensor isplaced posterior to the IO lens. In another embodiment, the photosensoris place anterior to the intraocular (“IO”) lens.

In one embodiment, the innovative photosensor measures and determinesboth the light intensity and distribution traversing the pupil, and thechange in light intensity received at individual sensor elements. Bymeasuring the light distribution, and change in light distribution, onthe photosensor array, the size of pupil is determined. By measuring thetemporal change in light intensity of illuminated sensor elements, anychanges in the ambient brightness is also determined. In thisembodiment, the changes in pupil size due to both the brightness reflexand the near synkinesis reflex can be determined, and the photosensorand range-finding apparatus can distinguish between both changing lightconditions and changes to the distance to the object of regard. Asdiscussed below, the ability to detect changes in relative light levelscan be used to distinguish between pupil reflex responses due to bothbrightness and synkinesis causes and can thereby accurately determinechanges in ambient brightness levels as well as the distance to anobject of regard.

In one embodiment, the pupil sizes of individual patients are measuredfor a variety of brightness and ocular convergence scenarios and abaseline established relating pupil size to various lighting andconvergence combinations. This baseline is used to program animplantable and custom IO photosensor, or integrated IO lens system suchthat accurate object distances can be determined and accurate focusachieved for each patient to take into account the idiosyncraticpupilary response. In another embodiment, only the synkinetic convergeresponse is measured and used to establish a baseline relating pupilsize to object distance. In still another embodiment, standardizedpupilary response baselines are created for sub-population groups, andthese baselines are used to program a standardized IO range-finder andsystem.

These and other features and objects of the invention will be more fullyunderstood from the following detailed description of the preferredembodiments that should be read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthe specification, illustrate the embodiments of the present inventionand, together with the description serve to explain the principles ofthe invention.

In the drawings:

FIG. 1 shows the anatomical structure of the eye;

FIGS. 2A-B show an example IOL system and implant according to oneembodiment of the present invention;

FIGS. 3A-F show examples of ocular convergence and the pupilarysynkinetic convergence reflex for various degrees of convergence, andexamples of the brightness reflex response of the pupil to varyingbrightness conditions;

FIGS. 4A-C depict tabulated data showing the estimated pupil sizes atvarious brightness levels and convergence conditions for differentpopulation groups according to one embodiment of the present invention;

FIGS. 5A-H show example photosensor chip designs according to exampleembodiments of the present invention;

FIGS. 6A-E show a front view of the photosensor of FIG. 5A and itselements, implanted behind a pupil, in various states depending on thesize of the pupil according to example embodiments of the presentinvention;

FIGS. 6F-H show a side-view of the photosensor of FIG. 5A and itselements implanted behind the pupil, in various states depending on thesize of the pupil according to one embodiment of the present invention;

FIG. 7A shows a process for determining the distance to an object ofregard according to one embodiment of the present invention;

FIG. 7B shows an example process for determining the distance to anobject of regard according to one embodiment of the present invention;

FIG. 7C shows an example look-up table for determining distance to anobject of regard according to one embodiment of the present invention;

FIGS. 8A-B show examples of a sensor array and electroactive lensintegrated onto a single chip according to various embodiments of thepresent invention;

FIG. 9 shows example positions of a photosensor integrated with oradjacent to a single electroactive lens according to various embodimentsof the present invention;

FIG. 10 shows the sensor “sandwiched” between two electroactive lenselements according to one embodiment of the present invention;

FIG. 11 shows an example non-electroactive multi-focal system using aphotosensor according to one embodiment of the present invention;

FIG. 12 shows an IOL system according to one embodiment of the presentinvention;

FIG. 13 shows an example general process for determining a distance toan object of regard and adjusting the multi-focal lens system using an10 photosensor to measure pupil size and determine distance to object ofregard according to one embodiment of the present invention;

FIGS. 14A-F show the photosensor and its elements in various statesdepending on the size of the pupil and the ambient light intensityaccording to one embodiment of the present invention; and

FIGS. 15 and 16 show an example process flow diagram for discriminatingbetween brightness and synkinetic reflex in order to determine thedistance to an object of regard.

DETAILED DESCRIPTION

FIG. 1 shows the anatomical structure of the eye 100 with labels,including: conjunctiva 110; ciliary body 112; iris 114; pupil 118;anterior chamber 116 (containing aqueous humor); crystalline lens 122;cornea 124; extraocular muscle 126; scelera 128; choroid 130; macula132; optic nerve 134; retina 136; vitreous humor 138; and capsular bag140. The crystalline lens 122 is encapsulated by a capsular bag 140.During a typical lens replacement surgery, the natural lens 122 isremoved from the capsular bag 140, and the new IOL is implanted insidethe capsular bag 140 by well known surgical techniques. The IOL can beinserted in a folded condition and then unfolded once inside thecapsular bag 140.

FIG. 2A shows an example of a multi-focal IOL system 210 implantedinside the capsular bag 140. FIG. 2B illustrates a blow up of the IOLsystem 210 shown in FIG. 2A. Referring to FIG. 2B, in one embodiment,the implanted IOL system 210 includes an electroactive lens 250 havingelectroactive elements capable of changing its refractive index inresponse to an applied voltage 260. A controller 270 determines thenecessary control signals to be sent to the electroactive lens 250, andan actuator 280 drives the electroactive lens element 250 via electrodesto alter its refractive index. In this embodiment, a photosensor chip290 having photosensor elements 520 (also referred to as photosensitiveelements) is configured in the form of a programmable range-finder whichis integrated with the lens system 210. The photosensor chip 290 (alsoreferred to as a range-finder photosensor or simply range-finder),described in more detail below, operates by detecting the arealdistribution of incident light that has traversed through the pupil 118and estimating the size of the pupil 118 based on the incident lightdistribution.

The pupil 118 is essentially circular and the amount and distribution oflight passing through the pupil 118, having undergone significantrefraction by the cornea 124, can be effectively represented as acircular beam having a radius equal to that of the pupil 118. Asdiscussed in more detail below, the pupil size is used to estimate thedistance to an object of regard, and based on this estimation, thecontroller 270 determines the appropriate focal length needed to bringthe object in focus and causes the actuator 280 to actuate theelectroactive lens 250, changing its effective refractive index in orderto bring the object of regard in focus (on the retina 136). The relativechanges of ambient brightness can also be measured by the range-finderphotosensor 290 and used to distinguish between and account for pupilsize changes resulting from different pupil reflex responses.

The above description is that of one embodiment only. Various otherembodiments, including different types of electroactive andnon-electroactive multi-focal lens systems are contemplated. Forexample, the IOL system components can also be modular and elements ofthe system can be placed outside the capsular bag 140 and even outsidethe eye 100. The details of the methods for determining the distance tothe object of regard and a variety of photosensor and IOL system designsare now described.

FIGS. 3A-E illustrate various degrees of ocular convergence andcorresponding pupil sizes 302 a-e, which, as described below, are usedto estimate object distance. The concept of ocular convergence is ameasure of how the lines of sight of each of the eyes 100 cross whenobjects are viewed at near distances. Generally, distance vision meansvision when viewing objects at a distance of greater than 20 ft (˜6meters) as shown in FIG. 3A (301 a), and near vision means vision whenviewing an object at less than 20 ft as shown in FIGS. 3B-3E (301 b-301e). In a normal human visual system, the process and mechanism ofbringing a near object (anything less than 20 ft) into focus is calledaccommodation, and during this process the eyes cross or converge ontothe object. As shown in FIG. 3A (301 a), there is zero convergence whenviewing an object at a distance of greater than 20 ft (the line of sightof each of the eyes is effectively parallel to one another). As theobject of regard is brought closer to the eyes, the degree ofconvergence increases as shown in FIGS. 3B-E (301 b-301 e).

Also shown in the illustrations is how the size (302 a-302 e) of the 118pupil differs for different degrees of convergence. Changes in the pupildiameter can be effected by the opening and closing of the iris 114.This is a result of a well understood pupilary reflex response known asthe synkinetic reflex response or “near synkinesis”. Particularly, inthis reflex, the pupil 118 changes its diameter in response to thecrossing of the eyes, or ocular convergence. The greater the degree ofconvergence, the greater the contraction of the pupils. This is shown inFIGS. 3A-E (302 a-302 e), the change in pupil diameters corresponding tothe degrees of convergence. More particularly, in FIG. 3A, when theobject of regard is at a distance, of 20 ft or more, the eyes aregenerally parallel, exhibiting no degree of crossing or convergence, andthe pupil synkinetic response is absent. As the object of regard isbrought nearer, as shown in FIGS. 3B-3E, the degree of convergenceincreases and the pupil's contract causing their diameter to decrease.For instance, as shown in FIG. 3A, a pupil may be about 6 mm in diameterwhen viewing a distant object. When the viewer regards an object at adistance of 10 feet, as shown in FIG. 3B, the eyes converge and thepupils contract, for example to 5 mm. In FIG. 3C, when the viewerregards an object at 5 feet, the degree of convergence increases and thepupils contract to, for example to 4 mm. In FIGS. 3D and 3E, when theobject viewed is for example 2.5 ft away, the eyes are even more crossedand pupils are even more constricted, e.g., 3 mm, and as the object isbrought to 10 inches the pupils may contract to about 2 mm. The actualvalue of pupil diameter for a given degree of convergence is variableand the examples given are for illustration only.

Another reflex is the pupilary brightness reflex which causes the pupildiameter to adjust to different levels of ambient brightness, generallycontracting in bright light and dilating in dim light in order tomaintain the optimum amount of light on the retina (i.e., retinalsensitivity). The pupil will dynamically adjust in size due to changesin ambient light conditions. Examples of the pupil diameter undervarious ambient light intensities are shown in FIG. 3F. This brightnessresponse is also well understood by those skilled in the art, forinstance, when the human eye 100 encounters a change in brightness,e.g., going from a dimly lit room to an outside sunny environment, thepupils 118 will contract to reduce the light intensity impinging on theretina. If the subject returns from the sunlit environment to a moredimly lit environment or room, the pupils will expand to allow for thecapture of more of the ambient light.

The degree of relative brightness impinging on a surface, or the amountof illuminance is commonly expressed in units of either lumens persquare foot, also known as foot-candles (ft-c), or lumens per squaremeter, also known as lux. Illuminance represents a photometricmeasurement of relative brightness conditions as perceived by the humaneye. As shown in FIG. 3F, examples of different brightness conditionsinclude direct sun (10000 ft-c or ˜100,000 lux); bright sky (3000 ft-cor ˜30000 lux); cloudy sky (500 ft-c or ˜5000 lux), a brightly litindoor room (100 ft-c or ˜1000 lux), a room with low level of lighting(20 ft-c or ˜200 lux), a very dimly lit room (0.5 ft-c or ˜5 lux), andnighttime starlit darkness (0.01 ft-c or ˜0.1 lux).

Although the pupil changes its diameter due to both the brightnessresponse and the synkinetic convergence reflex, the synkinetic reflexdue to convergence is the more predominant reflex (i.e., for typicaleveryday ranges of light levels, the synkinetic response contributesapproximately nine times more than the brightness reflex to thedetermination of pupil diameter when viewing near objects).

As described above, because of the synkinetic reflex, the pupil size ofan individual is related to the degree of convergence, and the degree ofconvergence is directly related to the distance from the eyes 100 to theobject of regard. The closer the object is, the smaller the pupils. Itis therefore possible to estimate the distance to the object of regardby determining the size of the pupil, because the size of the pupil, orchange in the size of the pupil, will be indicative generally of thedegree of convergence under specific levels or ranges of ambientbrightness. For example, due to the synkinetic response reflex, if thedistance to the object of regard is changed from 20 ft to 10 ft, theeyes must “cross” (i.e., each eye's line of sight converges) and thepupils will contract. If the object of regard is moved to 5 ft thepupils will contract to a smaller size. Likewise, if the object isbrought to within 1 ft, the pupils will contract further. Therelationship between the pupilary diameter and the distance to theobject of regard, or degree of convergence can be measuredidiosyncratically for each patient or benchmarked for an age group orother sub-population group as discussed further below.

FIGS. 4A-C depict tabulated data showing the estimated pupil sizes atvarious brightness levels and convergence conditions for differentpopulation groups. The pupil diameters are measured under variousbrightness levels and object distance combinations to establish the datatable for a respective population group. The data tables are used by therange-finder photosensor 290 to estimate the distance to the object ofregard and to drive the multi-focal IOL system 210.

These measurements can be carried out using standard ophthalmologic andoptometric techniques including using a pupilometer to determine pupilsizes at various distances (degrees of convergence). For example, thiscan be accomplished using refractometers and the like, to adjust theapparent distance to a test object thereby causing the patient to crossthe eyes as they would when viewing an object at that distance, as willbe apparent to those skilled in the art. The brightness response of thepupil can also be measured using standard optometric procedures, forinstance, by varying the brightness impinging on the eyes of anindividual, and using a pupilometer to measure the pupilary size. Abaseline curve or table can be established that relates pupil size toambient brightness.

The pupilary brightness and synkinetic responses to varying brightnessconditions and object distances respectively are well understood.Generally, the degree of pupilary response, and the maximum extent towhich the pupil can constrict or dilate decreases with age. Referring tothe exemplary tables of FIGS. 4A and 4B, the pupils of an average 20year old may constrict maximally to a size of 2 mm and dilate maximallyto a size of 7 mm, whereas an the pupil of an average 70 year old maymaximally constrict to a size of 2.5 mm and dilate maximally to a sizeof 5 mm. And as shown in FIG. 4C, an average 40 year old's pupils maymaximally constrict to 2.3 mm and dilate maximally to 6 mm for example.

Also shown in FIGS. 4A-C are the relationships between pupil size andbrightness which can be used to establish object distance for anindividual patient of the population group. An intraocular sensor andprocessor, described below, are used to detect incident light,traversing the pupil, estimate the pupil size and relative brightness,and estimate the distance to the object of regard by comparing themeasured data with the patient baseline data. This process isrepresented in FIGS. 7A and 7C, discussed below.

In one embodiment, an intraocular photosensor design and method is usedto measure pupil diameter and changes thereto by detecting changes ofincident light intensity and distribution through the pupil. The pupil118 size can be used to derive the distance to an object of regard andthis information used to adjust the focal length of the multi-focal IOLsystem 210.

FIGS. 5A-H show various intraocular photosensor chip (or sensor array)designs 500 a-500 h according to example embodiments. Particularly,FIGS. 5A-H depict front views of the photosensor element designs. In oneembodiment, shown in FIG. 5A, the photosensor (or photo-sensitive)elements 520 a are arranged in two orthogonal linear arrays on, forinstance, a semiconductor wafer or microchip. Various photosensitivematerials and photosensor technologies are well known in the art andcould be utilized including but not limited to charge-coupled device(“CCD”) and complementary metal-oxide semiconductor (“CMOS”)technologies. Referring to FIG. 5A, for illustrative purposes the “legs”510 a of the linear arrays have been labeled, N, S, E, and W, but itshould be clear that any orientation of elements that can measure lightintensity over an increasing linear distance (e.g., radius) from thecenter 515 a of the photosensor chip 500 a could be employed. Forinstance FIGS. 5B-H show other examples of photosensor elementorientations on a semiconductor chip or wafer, but others are alsopossible as will be evident to those skilled in the art.

The photosensor chips 500 a-500 h in FIG. 5A-5H are approximately thesize of a fully dilated pupil, e.g., 7 mm, and are oriented such thatthe plane of the disc of the sensor is parallel to the plane of thepupil. By matching the photosensor diameter and length of thephotosensor elements 520 a-520 h to the maximum size of the pupil 118,the full range of pupil diameters can be monitored and detected. Thephotosensor chips 500 a-500 h could be larger or smaller depending onthe desired application as will be evident to those skilled in the art.

FIGS. 6A-C show the photosensor chip 500 a of FIG. 5A and itsphotosensor elements 520 a, implanted behind the pupil 118, in variousstates depending on the size of the pupil 118, and how the photosensorchip 500 a can be used to measure the size of the pupil 118. As shown,only those photosensor elements 520 a behind the pupil receive all (orthe vast majority) of photo stimulus. The photosensor's elements outsidethe pupil receive little or no photo stimulus.

FIGS. 6F-H show a side-view of the photosensor chip 500 a (FIG. 5A) andits photosensor elements 520 a, implanted behind the pupil 118, invarious states depending on the size of the pupil 118 corresponding toFIG. 6A-C. For clarity, the figures show only the pupil 118 and thephotosensor chip 500 a of the IO system (e.g., FIG. 2B, 210) behind thepupil 118, (e.g., implanted intraocularly) corresponding to the pupildiameters in FIGS. 6A-C.

FIGS. 6A and 6F show a 4 mm pupil 118 and that only the photosensorelements 520 a within the central portion (4 mm circle) of thephotosensor are illuminated. The photosensor elements 520 a outside thepupil 118 diameter receive little or no light. FIGS. 6B and 6G show afully dilated pupil 118 and the photosensor chip 290 a in which agreater number of photosensor elements 520 a are illuminated (e.g.,central 7 mm circle of the sensor). FIGS. 6C and 6H show a fullycontracted pupil 118 wherein only the very central portion of thephotosensor chip 500 a and corresponding sensor elements 520 a areilluminated. Only those elements within the central approximately 2 mmarea of the sensor array receive the ambient light, where those furthertoward the periphery receive little of no light. These values werechosen as illustrative only. Generally the diameter of pupil 118 in ahealthy young adult is maintained between 2 and 7 mm, whereas the rangeis somewhat less in an older patient, and 4-5 mm represents andintermediate value. In each of these cases, a specific distribution ofsensor elements 520 a are illuminated depending on the size of the pupil118, and the pupil size is thereby determined. Although in oneembodiment, there are eight sensor elements 520 a per leg 510 a of thephotosensor chip 500 a in addition to a central photosensor element 515a, the number and orientation of the sensor elements 520 a can beadjusted depending on the application.

FIGS. 6D-E show another representation of how the individual photosensorelements 520 a would be “activated” depending on the pupil 118 size andlight intensity. Because of different ambient light intensities, in someembodiments the sensor array can be programmed to various levels ofsensitivities depending on the ambient light detected. For instance, ina dimly lit or dark environment, the photosensors elements 520 a maydynamically adjust (either automatically or on instructions from acontroller e.g., FIG. 2B, 270) to an increased sensitivity, whereas in abright environment, the photosensor elements 520 a may adjust to alessened sensitivity.

FIG. 6E shows how the programmable photosensor chip 500 a might registernot only light distribution, but also intensity of that distribution. Inone embodiment, the sensor elements 520 a are programmed to register anddistinguish between gradations of intensity. In this example, there are5 different intensity levels, but as evident to those skilled in theart, the photosensor chip 500 a could be designed and programmed todistinguish between any intensity in light levels. Preferably, the IOLsystem can distinguish between and register relative changes in lightintensity to discriminate between the brightness reflex and thesynkinetic reflex as discussed further herein. Also, the potential forscattered light to reach sensor elements 520 a outside the area of thepupil 118 is possible, and the photosensor chip 500 a can be programmedto discard such “noise” by establishing threshold levels of intensityand contrast.

The photosensor chip 500 a can be designed with varying degrees ofsensitivity as desired, e.g., in order to discriminate between a varietyof lighting and visual conditions. Some light (e.g., scattered) mayreach the photosensor elements 520 a outside the pupil 118 area region.A variety of photo-detectors with varying brightness and spectralsensitivities could be used as photosensors in the present embodiment.In addition, a signal processing algorithm of the received light signalcan be adjusted to distinguish between different lighting conditions anddistinguish between the relative amount of light received by thephotosensors not within the area of the pupil and those within the areaof the pupil.

As described further herein, the pupil diameter can be determineddirectly from the photosensor chip 500 a itself (e.g., the area of thephotosensor that is illumined beyond a given threshold correspondsdirectly to the area of the pupil 118) or determined via a postprocessing signal algorithm customized to the application. The pupil 118diameters and photosensor array design 500 a shown are examples only,and those skilled in the art will know that the pupil diameter can varycontinuously between upper and lower limits and that the embodimentshown can readily be used to determine pupil diameter at any valuebetween these limits, and further that other sensor designs will alsooperate to detect incident light and thereby determine the size of thepupil. As discussed elsewhere, in one embodiment, the pupil sizemeasurement is used to determine the distance to an object, and thisdistance is used by a controller (e.g., FIG. 2B, 270) to drive themulti-focal lens system 210 to adjust its focal properties to bring theview object in focus.

Because the photosensor chip (e.g., FIG. 2, 290; FIG. 5A, 500 a) will bepositioned posterior to the pupil 118 and anterior to the retina 136, itshould be sufficiently transparent not to occlude too much of theincident light which would negatively impact vision. Thus, although theindividual photosensor elements would be opaque, i.e. they would absorbthe incident light, the number of sensor elements and the area theyoccupy is chosen such that the amount of incident light that they absorbis sufficient to distinguish between various pupil sizes, butsufficiently small relative to the overall incident light not to impactvision. In one embodiment the array is 95% transmissive. In anotherembodiment, the array is 90% transmissive. Other transmission profilesare possible. The photosensor chip design limits the number ofphotosensor elements to what is necessary to radially detect changes inincident light intensity while allowing most of the light through toreach the retina 136 (FIGS. 1, 2A) and is optimally designed to achievethe desired photosensor operation and detection while not impactingvision through photon attenuation. In one embodiment, individual sensorelements can be “turned off”, e.g., electrically controlled to altertheir states from a photo detector to an essentially inactive andtransmissive element, thus allowing for a dynamic variation in thenumber of photosensor elements that are active, for instance for varyinglight levels, and the transmission profile of the photosensor.

Both the brightness reflex and the synkinetic reflex can affect pupildiameter. If the distance to the object of regard is constant, anychange in the pupil's diameter will be primarily due to the brightnessresponse, the response due to a change in ambient light level.Conversely, if the brightness level is relatively constant, and changein the pupil's diameter will be primarily due to the synkineticresponse, the response due to a change in the distance of the object ofregard. In everyday life, however, most individuals will encounterwidely varying brightness level, and will also continuously shift theirgaze and focus to behold objects of regard at different distances, somefar off and some close up. Thus, both the brightness reflex and thesynkinetic reflex may have a significant and coincident impact oncausing the pupil 118 to change size according to the brightness leveland the distance to the object of regard. Preferably, the IOL system 210described above measures both brightness levels and pupil diameter, andthese two data inputs, together with patient benchmark data, are used toestimate the distance to the object of regard in one embodiment.

In one embodiment, a benchmark relationship of the pupil 118 responseand size to both changing brightness levels and changing distances ofregard is established by measuring patient pupil diameter under avariety of brightness and convergence conditions using standardoptometric techniques as already described. As described above, FIGS.4A-C illustrate one set of measurements for different population groups,but it is to be understood that such measurements and data tabulationcould be taken for individual patients and used to customize therange-finder photosensor chip 290 to each patient.

FIG. 7A illustrates an exemplary process 700 a for determining thedistance to an object of regard according to one embodiment, and FIG. 7Cshows a look-up table for determining distance to an object of regardaccording to one embodiment. In block 705, an intraocular photosensorchip 290 (FIG. 2A) detects both the spatial extent and intensity oflight incident through the pupil. An estimate of both pupil diameter andambient intensity are derived in blocks 710,715, e.g., via a processorintegrated with the photosensor chip 290. The estimated pupil diameterdetermined in block 710 and brightness level determined in block 715 arethen compared with the patient benchmark data using a comparator toestimate the distance to the object of regard, as shown in block 720. Inone embodiment, the patient benchmark data (e.g., as in FIGS. 4A-C) isstored in processor memory in block 725. This data includes pupil sizesfor various brightness and object distance combinations. The measuredpupil size and brightness are compared in block 720 to the benchmarkdata stored in block 725 and an estimate of object distance is derivedin block 730. An example of a look-up table for a patient is shown inFIG. 7C. For example, using the patient benchmark data of FIG. 7C, ifthe pupil size is estimated to be 4.1 mm and the relative brightness isestimated to be 1 ft-C, then the object distance would be estimated tobe 1.2 meters. Similarly, if the pupil size is estimated to be 4.1 mmand the relative brightness is estimated to be 100 ft-C, then the objectdistance would be estimated to be at a distance of at least 6 meters. Aswill be evident to those skilled in the art, the processor comparatorand distance estimator logic can be accomplished via a number oftechniques including look-up tables or real-time weighted algorithmiccomputations.

FIG. 7B illustrates an exemplary process 700 b for determining thedistance to an object of regard according to another embodiment. Inblock 735 light entering the pupil is detected. In this embodiment, anestimate of the pupil size change and the brightness change from a priorpupil state are determined as shown in blocks 740, 745, respectively(e.g., from the measurement shown in FIG. 7A). Using patient benchmarkdata stored in block 725, a discriminator estimates the amount of pupilchange that is due to the change in brightness, as shown in block 750.In block 755, the estimated pupil size change due to a change in objectfocus, near-synkinesis, is then determined and based on that estimate anestimate of the change in distance to the object of regard is determinedin block 760. Discriminating between changing brightness levels andpupil size changes due to the changes allow the distance to an object ofregard to be estimated as discussed further below.

A photosensor element array can exist as a separate component or beintegral with other components of the IOL system. In one embodiment,shown in FIG. 8, the photosensor array is integrated with the lenselement on a single chip. In this embodiment, the photosensor array 805and electroactive lens 810 are integrated on a single semiconductivewafer 815, the chip including the photosensor elements 820,electroactive elements 825 and associated circuitry. Particularly, theelectroactive lens portion of the chip 810 consists of a thin layer ofelectroactive lens elements 825 in the form of a pixelated array. Anexample of such a lens is described in U.S. Patent Publication20060095128, incorporated herein by reference. The orientation of numberof photosensor elements 820 can be adjusted depending on the application(e.g., as described above with respect to the sensor designs shown inFIGS. 5A-H).

In another embodiment, shown in FIG. 8B, the photosensor array 805 is aseparate chip that is placed either on the pixelated lens array 810(e.g., attached to the front or rear of the lens chip) or placedadjacent to the lens (in front or in back).

FIG. 9 shows other embodiments including, a photosensor 901 as part ofan IO lens system 900. This embodiment uses a non-pixelatedelectroactive lens 905. For example, such a lens system is described inU.S. Pat. No. 6,638,304, incorporated herein by reference. Theelectroactive lens 905 includes an electroactive lens material (e.g.,nematic) that is attached to a transparent electrode 910. In oneembodiment, the photosensor 901 is placed between the electroactive lens905 and the transparent electrode 910. In another embodiment, theelectroactive lens 905 is placed in front of the photosensor 901 lens.In another embodiment the electroactive lens 905 is placed behind thephotosensor 901 (front refers to the direction oriented toward the frontof the eye; i.e., closest to the pupil).

FIG. 10 shows a photosensor 901 “sandwiched” between two electroactivelens elements 1005 according to one embodiment. Also shown are twotransparent electrodes 910. The electroactive lenses 1005 are controlledby a controller 1010.

In still other embodiments the photosensor array is integrated with,attached to, or placed adjacent to a variety of IOL designs, includingthose IOL systems which utilize non-electroactive lenses, includingdeformable lenses that are deformably adjusted via mechanical or otherforces, movable lens systems including multi-lens system, and generallywith any lens system capable of adjusting its focal length. FIG. 11shows an example of how a photosensor 901 would be used with anon-electroactive multi-focal system including a fixed lens 1110 and afocusing lens 1105.

In one embodiments shown in FIG. 12, a photodetector sensor array isintegrated with a multi-focal lens optic and associated controller andactuator, and used to determine the range to an object of regard, therelative ambient brightness level and changes thereto, or both. Thesensor array is a programmable array in one embodiment. The degree anddistribution of illumination of the sensor elements is indicative of thelight distribution and intensity at any given moment traversing thepupil, and this data is used to determine the size of the pupil at ornear that moment. In one embodiment, the number of or pattern ofphotosensor elements that are activated (i.e., receiving above thresholdlight intensity) and in some cases the degree of light intensity is useddirectly by the controller to drive the lens element. In anotherembodiment the data representing the illumined photosensor elements isfurther processed, for example by algorithmic processing or comparedwith a look-up table, to determine the distance to the object of regard,e.g., by determining the pupil size and deriving the object distancefrom a known pupil response baseline.

Particularly, FIG. 12 shows a block diagram of an IOL system 1200including sensor 1210 for detecting incident light and for determiningpupil size, or a change in ambient light intensity, or both, to derivethe distance to the object of regard. A microcontroller 1205 for dataprocessing and instruction control, an actuator 1220 for driving thefocusing element, and the multi-focal lens element 1215 are alsoincluded. A power source (or energy source) 1225 supplies power to thecontroller 1205, the range finding photosensor 1210, and the actuator1220.

FIG. 13 shows the process 1300 for determining a distance to an objectof regard and adjusting the multi-focal lens system according to oneembodiment. At block 1305, the light distribution received through thepupil is measured. Pupil size based on the incident light is determinedat block 1310. In turn, distance to an object of regard based on pupilsize is determined at block 1315 and at block 1320 the focal length ofthe lens system appropriate for the object distance is determined. Atblock 1325 an actuator is driven to adjust lens focus.

As shown in FIG. 13, the microcontroller 1330 is encoded withinstructions for performing blocks 1310-1325 of process 1300. This canbe implemented in firmware or software. In an embodiment theinstructions are encoded directly in hardware (e.g., an asic). Theinstructions can be encoded on a single chip along with the pixelatedarray (not shown) and photosensor 1335. The instructions on themicrocontroller include instructions for receiving data from thephotosensor 1335 data and for determining the distance to the object ofregard. For example, the raw data from the photosensor 1335 may causethe microcontroller 1330 to issue instructions to the actuator, whichthen actuates the lens system to effect the focal length change. In suchan arrangement, a specific group or orientation of activated orillumined elements of the photosensor 1335 cause the focusinginstruction of the microcontroller 1330 to be executed. Thisfunctionality can be implemented via a look-up table or similar. Thetable would represent a mapping between sensor element illuminationpatterns (representing a target distance) and the focal power neededfrom the lens system.

Alternatively, the data from the photosensor 1335 may be processedfurther by the microcontroller 1330 and the results of thispost-processing computation used by the microcontroller 1330 to instructthe actuator, which alters the focal length of the system. The overalloperation and result is that based on the input from the photosensor,the distance to the object of regard is determined or estimated and thenecessary focusing power determined and the actuator driven to act onthe lens system in order to change its index of refraction in order toobtain the desired power. A power source supplies power to thecontroller, the range finding photosensor, and the actuator. A singlepower source can supply all three, e.g., in the case of an integratedrange finder sensor, actuator and lens system, or separate power sourcescan provide each component with power. The power supply for the systemcan be a rechargeable energy storage device such as a battery,capacitor, or other energy store as are well known in the art. Examplesof energy generation means include photoelectric, thermoelectric, andpiezoelectric transducers capable of capturing photonic, thermal, andmechanical energy respectively, for use or storage by the system. Energytransfer and storage by inductively coupling, laser or RF energy areother examples, but the invention is not limited to any specific powergeneration or storage means.

The IOL system in one embodiment has continuously varying focalproperties and powers. In another embodiment the lens system is limitedto a number of specific focal powers. For example, the system may beconfigured to adjust continuously in 0.1 D increments between +2 and −10D, or the system may be designed to have only 3 different focal powers,e.g., 0 D for distance vision, 1 D for intermediate vision and 3 D fornear vision. Depending on the specific application or desire, a widerange of options are available from the system, including the degree ofexactness in determining the distance to the object of regard, and therange and sensitivities and ability to tune the focusing power of thesystem.

As described above, accurate determination of the distance to objects ofregard can be accomplished by measuring the pupil size and ambientbrightness level and comparing those measurements against an empiricallyestablished patient pupil size baseline. This range-finding capabilitycoupled with a adjustable multi-focal lens system allows the lens systemto be appropriately adjusted to focus on the object of regard. Patientor population baselines relating pupil size and changes in pupil size inresponse to changing brightness and changing object distances can alsobe created to allow for further refinement and accuracy inrange-finding. As described below, the change in the intensity ofillumination of individual photosensors provides a measure of thechanges in ambient brightness, and this data can be used discriminatebetween the pupilary reflex responses, and resolve ambiguities.

For instance, an individual may be transitioning from one level ofbrightness to another level of brightness, the change in brightnesslevel causing a significant pupilary brightness response. For instance,leaving an indoor environment and walking outside into bright sunlight,or turning on a bright light in a previously darkened room, could resultin several orders of magnitude change in ambient brightness andsignificant pupilary constriction. The converse of these situations,i.e., proceeding from a brightly lit environment, to relative darknesswould potentially result in significant pupilary dilation. In thesecircumstances, the pupilary brightness response may temporarily (e.g.,until the retina adjusts) dominate the synkinetic response and the rapidchange in pupil diameter would not necessarily be an indication that thedistance to the object of regard has changed, but rather that the levelof brightness has changed.

In one embodiment, temporal changes in brightness levels of individualsensor elements are measured and used to distinguish and resolve anypotential ambiguities. By measuring the change in relative brightness asa function of time at each individual sensor element allows the systemto determine, for instance, whether brightness is increasing ordecreasing.

FIGS. 14A-F show hypothetical scenarios that may result in the pupilchanging size due to the brightness reflex, and how the range-finderphotosensor would distinguish pupilary response due to brightness levelchanges. The number of photosensor elements 520 that are illuminatedabove a threshold level provides information to determine pupil size.The change in the intensity of illumination at each sensor elementindicates changes in ambient light level.

FIG. 14A shows a pupil diameter of 4 mm of a subject's eye while viewingan object at 1 m (1 diopter) in a bright room, e.g., a brightness of 100ft-c. The central photosensor elements 520, corresponding to pupildiameter of 4 mm, are illuminated with a relative intensity of 100. Thispupil diameter of 4 mm in a relative brightness of 100 corresponding toa object of regard distance of 1 m-requiring 1 diopter of convergenceaccommodation may be obtained from the individual patient baselinemeasurements as discussed above according to one embodiment. FIG. 14Bshows a case where the room light is dimmed to 10 ft-c, which, forexample, causes the pupil to dilate to 5 mm. Additional peripheralphotosensor elements are illuminated due to the increase pupil size,however, the relative intensity of the central sensors, corresponding tothe original pupil size of 4 mm, drops to 10. This decrease in intensityof the inner sensor elements and concurrent increase in the number ofphotosensor elements 520 illuminated indicates to the system that thepupil dilated because of a decrease in relative brightness, and notbecause the distance to the object of regard had changed. A similareffect is shown in FIG. 14C where the light is further dimmed to 1 ft-c.In this case, the pupil dilates and the number and radial extent ofphotosensor elements 520 illuminated increase, thereby indicating anenlargement of the pupil while the sharp decrease in luminance to arelative value of one (1) indicates that pupil dilatation was due to thechange in brightness level and not a change in the distance to theobject of regard. The range-finding system or controller in thissituation, according to one embodiment, would correlate the pupil changewith the change in relative brightness, and not due to a change indistance to the object of regard, and the IO multi-focal system wouldnot alter the focal length in is instance.

FIG. 14D shows a pupil diameter of 4 mm of a subject's eye while viewingan object at 1 m (1 diopter) in a bright room, e.g., a brightness of 100ft-c. The central photosensor elements 520, corresponding to a pupildiameter of 4 mm, are illuminated with a relative intensity of 100. FIG.14E shows the case where the room light is brightened to 500 ft-c,which, for example, causes the pupil to contract to 5 mm. The mostperipheral photosensor elements 520 that were illuminated at 100 f ft-care no longer illuminated due to the decrease in pupil size caused bythe brightness reflex. However, the relative intensity of the centralphotosensor elements, corresponding to the new pupil size of 3 mm,increase to 500. This increase in intensity of the inner photosensorelements and concurrent decrease in the number of sensors illuminatedindicates to the system that the pupil contracted because of an increasein relative brightness, and not because the distance to the object ofregard had changed. A similar effect is shown in FIG. 14F where thepupils encounter a light intensity increased to 2500 ft-c (e.g., brightsky). The pupil constricts, perhaps maximally, and the number and radialextent of photosensor elements 520 illuminated decreases, therebyindicating the contraction of the pupil, while the sharp increase inrelative luminance to a value of 2500 indicates that pupil contractionwas due to the change in brightness level, and not a change in thedistance to the object of regard. The range-finding system or controllerin this situation, according to one embodiment, would correlate thepupil change with the change in relative brightness, and not due to achange in distance to the object of regard, and the IO multi-focalsystem would not alter the focal length in is instance.

Generally, these embodiments provide a way to accurately determine therange to an object of regard utilizing an intraocular photosensor andprocessor to measure pupil size and determine object distance whiletaking into account changes in ambient brightness levels. If therelative brightness increases or decreases significantly and rapidlyenough such that the pupilary brightness reflex contributes asignificant amount to pupilary size change, the system will estimate ordetermine whether and to what extent the pupilary contraction ordilation is due to brightness reflex versus the synkinetic reflex, andthereby accurately and continuously determine the distance to the objectof regard even under conditions of changing relative brightness.

FIGS. 15 and 16 shows example generalized process flow diagramsaccording to other embodiments for determining distance to objects ofregard under varying conditions of brightness. Each involve initiallyestablishing an individual patient or population group baseline, ofpupil size and changes thereto in relation to varying and changingbrightness and near-converge scenarios. These baselines can be createdfor example through empirical measurements in the clinician's office orwith reference to the literature, and the baseline can include as manyor as few parameters and data points as necessary for the specificapplication need and sensitivity. The baselines are used as programminginput to the IO range-finder system, which comprises a sensor unit formeasuring light which has traversed the pupil and estimating, the sizeof the pupil, the relative brightness level, and changes to thosephysical variables. As will be evident to those skilled in the art avariety of mathematical methods, including weighted algorithms, neuralnetworks, and others known in the art could be used to establish suchbaselines and a variety of processing means (e.g., asic) could be usedto implement the correlation functionality correlating the baseline tothe measured intraocular light distribution and intensity changes.

Referring to FIG. 15, at block 1502, radiation at each sensor element isdetected. At block 1504 a light intensity level and a rate of changed/(dt) of intensity at each sensor element is determined, which is fedto block 1506. As shown in FIG. 15, blocks 1504 and 1506 can be twoseparate processes operating in parallel. Block 1506 determines aspatial distribution of intensities detected by the sensor elements andindicates a spatial intensity distribution of light traversing thepupil. A change in the spatial distribution, d/(dt) (spatialdistribution) is determined at block 1510. Block 1512 uses theinformation obtained in block 1510, along with an estimation of ambientbrightness level and a change in brightness, d/dt (brightness), obtainedin block 1508, to estimate pupil size and a change in pupil size, d/(dt)(pupil size).

At block 1520 a patient baseline is initiated by measuring pupil sizesfor a variety of brightness levels and object distances and combinationsthereof. At block 1522 (either in parallel or sequentially), changes topupil size for a variety of changing brightness and object distances aremeasured. Based on the information obtained from blocks 1520 and 1522,at block 1524, a general relationship or curve relating to pupil sizeand/or size changes, response times, etc., are derived and/or fitted, asthe case may be, to brightness levels, object distances, changes ofbrightness and distance, and combinations of each. At block 1514 themeasured and computed data are correlated with a generalized curve orlookup table and at block 1516 the distance to the object of regard isdetermined. At block 1518 a change in the distance to the object ofregard is determined.

Referring to FIG. 16, at block 1602 incident light distribution andintensity are measured and at block 1604 the intensity registered byeach sensor element to a previous measured value at that element iscompared. In addition, at block 1610 a pupil size is determined based onthe distribution of incident light (e.g., radial). A determination ismade at block 1606 whether a change in intensity exceeds a threshold Δ(+1/−). If not, then at block 1608 a distance to an object of regard iscomputed based on pupil size.

If the change exceeds the threshold, then at block 1612 a change inrelative brightness is determined from previous measurement and at block1618 an expected change in pupil size due to brightness change isdetermined (or computed). Following from blocks 1612 and 1616, at block1620, a change in pupil size is correlated with a change in brightnessto correct for brightness response. Based on this information at block1622 a distance to object of regard is determined.

In one embodiment the pupil size of each patient is measured under 9different conditions of light intensity and distance (convergence) inorder to establish the patient pupil response baseline; the pupil sizeis measured at low, medium, and high levels of brightness (e.g., 0.01,25, 100 ft-c) for each of the 3 distance measurement (20 ft, 10 ft, 1ft). In another embodiment, only 2 measurements of brightness are takenfor each distance. In yet another embodiment, 6 levels of brightness aremeasured, for each of 6 different distances, requiring a total of 36measurements. Any number of combinations is possible depending on theapplication and sensitivity. The data obtained can be interpolated andextrapolated to obtain a relationship curve covering each combination ofbrightness and distance to object as will be evident to those skilled inthe art. In some embodiments, experimental data is obtained andcorresponding pupil response relationships are established for thegeneral population, population subgroups, and individual patients.Experimental data could be obtained and corresponding relationshipsbetween pupil size and brightness level could be established for thegeneral population, population subgroups, for example based on age, orindividual patients, and these data used to provide various levels ofcustomization and fine-tuning of focusing depending on the individual orpopulation group.

In another embodiment, not only is the resulting pupil size determinedfor a variety of lighting and target distance combinations, but theactual pupil response, e.g., how it changes in size, the speed anddegree of overshoot or fine-adjustment with concurrent ornear-concurrent changes in both light level and target distance aremeasured and these data used to more accurately determine anindividual's baseline response for most real-world conditions.

By benchmarking and establishing individual or population specificpupilary response that take into account both the effect of the relativebrightness and object distance on pupil diameter allows for accuratedetermination of the distance to the object of regard in a variety oflighting conditions utilizing embodiment of the invention. In oneembodiment, each IOL system is customized to each individual patient, byprogramming the IO controller such that the pupil sizes determined invarious light levels will result in accurate determination of objectdistances and result in optimum focus for that individual patient.

Although this invention has been illustrated by reference to specificembodiments, it will be apparent to those skilled in the art thatvarious changes and modifications may be made which clearly fall withinthe scope of the invention. The invention is intended to be protectedbroadly within the spirit and scope of the appended claims.

1-81. (canceled)
 82. A method for adjusting a multi-focal intraocularlens system to bring an object of regard into focus, comprising:measuring a spatial distribution of light traversing a pupil; estimatinga distance to the object of regard based on the spatial distribution;and adjusting a focal length of the multi-focal lens system based on thedistance to bring the object of regard into focus.
 83. The method ofclaim 82, wherein measuring the spatial distribution of light traversingthe pupil is accomplished by a photosensor implanted in an eye, andestimating a pupil size and the distance to an object of regard isperformed by a processor.
 84. A method for taking into account pupilsize changes due to respective variations in ambient brightness whendetermining changes in distance to an object of regard based on pupilsize measurements, comprising: discriminating between a pupilarybrightness reflex and a synkinetic reflex using an intraocularphotosensor and a processor to measure and estimate a pupil size, alight intensity, a change in a the light intensity, and a degree ofocular convergence; and estimating a distance to an object of regardbased on said discriminating.
 85. A method, comprising: detectingincident light through a pupil; estimating a size of the pupil;estimating a relative brightness of the incident light; and estimating adistance to an object of regard.
 86. The method of claim 85, furthercomprising: estimating a change in the size of the pupil from an earliertime; estimating a change in the relative brightness from the earliertime; and estimating a change in distance to an object of regard fromthe earlier time.
 87. The method of claim 85, further comprising: inresponse to at least one of the distance to the object of regard and achange in the distance, adjusting at least one of a focal length and anindex of refraction of a multi-focal lens system to bring the object ofregard into focus.
 88. An intraocular photosensor for measuring lightthat has traversed a pupil of an eye comprising: means for detecting aspatial distribution of light; means for detecting a change in thespatial distribution; means for detecting a plurality of relativeintensities; means for detecting changes of the plurality of relativeintensities; and means for estimating a pupil size based at least inpart on at least one of the change in the spatial distribution and thechanges of the plurality of relative intensities.